The epitranscriptomic writer ALKBH8 drives tolerance and protects mouse lungs from the environmental pollutant naphthalene

ABSTRACT

The epitranscriptomic writer Alkylation Repair Homolog 8 (ALKBH8) is a transfer RNA (tRNA) methyltransferase that modifies the wobble uridine of selenocysteine tRNA to promote the specialized translation of selenoproteins. Using Alkbh8 deficient (Alkbh8^def) mice, we have investigated the importance of epitranscriptomic systems in the response to naphthalene, an abundant polycyclic aromatic hydrocarbon and environmental toxicant. We performed basal lung analysis and naphthalene exposure studies using wild type (WT), Alkbh8^def and Cyp2abfgs-null mice, the latter of which lack the cytochrome P450 enzymes required for naphthalene bioactivation. Under basal conditions, lungs from Alkbh8^def mice have increased markers of oxidative stress and decreased thioredoxin reductase protein levels, and have reprogrammed gene expression to differentially regulate stress response transcripts. Alkbh8^def mice are more sensitive to naphthalene induced death than WT, showing higher susceptibility to lung damage at the cellular and molecular levels. Further, WT mice develop a tolerance to naphthalene after 3 days, defined as resistance to a high challenging dose after repeated exposures, which is absent in Alkbh8^def mice. We conclude that the epitranscriptomic writer ALKBH8 plays a protective role against naphthalene-induced lung dysfunction and promotes naphthalene tolerance. Our work provides an early example of how epitranscriptomic systems can regulate the response to environmental stress in vivo.

KEYWORDS:

• Epitranscriptomics
• RNA modification
• tolerance
• naphthalene
• ALKBH8
• selenoprotein
• translation
• stress response

Acknowledgments

We would like to thank our colleagues who have provided helpful suggestions. We would also like to thank the dedicated animal care staff at the University and Albany, Wadsworth Institute, and University of Arizona for their helpful assistance in all issues related to our animal colonies and Ms. Weizhu Yang for assistance with mouse breeding.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data of this article can be accessed here.

Additional information

Funding

This work was supported by the National Institute of Environmental Health Sciences [R01ES020867]; National Institutes of Health [P30ES006694]; National Institutes of Health [R01ES026856]; National Institutes of Health [R01ES024615)], and the National Research Foundation of Singapore through the Singapore-MIT Alliance for Research and Technology.